Earnings (Loss) Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Earnings Per Share [Abstract]
Net earnings (loss)	$ 33,898	$ (52,497)
Less: earnings allocated to participating securities	171	0
Earnings (loss) available for common shareholders	$ 33,727	$ (52,497)
Basic earnings (loss) per share (in dollars per share)	$ 0.62	$ (0.98)
Diluted earnings (loss) per share (in dollars per share)	$ 0.61	$ (0.98)
Weighted average shares outstanding-basic (in shares)	54,759,000	53,866,000
Add: Dilutive effects of stock options and RSUs (in shares)	504,000	0
Weighted average shares outstanding-dilutive (in shares)	55,263,000	53,866,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	300,000	1,900,000

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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The earnings that is allocated to common stock and participating securities to the extent that each security may share in earnings as if all of the earnings for the period had been distributed.

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